Isolation and Identification of Wheat-Associated Fungi, Screening of Antagonistic Bacteria, and Medium Optimization

Wheat is highly susceptible to postharvest mold contamination, posing significant threats to food safety and economic stability. This study isolated and identified 40 fungal strains from stored wheat, with <italic>Alternaria</italic> as the predominant genus. <italic>Bacillus velezensis</italic> MY1 exhibited broad-spectrum antagonism against key pathogens including <italic>Alternaria alstroemeriae</italic>, <italic>Chaetomium globosum</italic>, and <italic>Aspergillus aflatoxiformans</italic>, with an average inhibition rate of 67.56%. Orthogonal optimization defined a fermentation medium comprising sucrose (30 g/L), beef extract (20 g/L), and K₂HPO₄ (5 g/L), which enhanced biomass yield 2.4-fold compared to conventional LB medium.